1. Field of the Invention
The present invention relates to an elongated sanitary napkin suitable for nighttime use. More particularly, the invention relates to a sanitary napkin in which an absorbent region is defined by compressed grooves formed in its skin-side surface.
2. Description of the Related Art
Elongated sanitary napkins of the type having an elongated absorbent region that is surrounded by a compressed groove formed in its skin-side surface have been known as being suitable for nighttime use.
For example, Japanese Unexamined Patent Publication No. 2001-95842 (Patent Publication1) and Japanese Unexamined Patent Publication No. 2002-656 (Patent Publication 2) disclose elongated sanitary napkins each having longitudinally extending leakage preventing walls disposed on right and left sides of the skin-side surface. In the region between the right and left leakage preventing walls, an elongated absorbent region is surrounded by a compressed groove. The compressed groove is formed by compressing a liquid absorbent layer together with a liquid-permeable topsheet appearing on the skin-side surface.
In sanitary napkin of this kind, since the absorbent region surrounded by the compressed groove is raised toward the skin-side, the absorbent region can easily be kept in close contact with the vaginal opening of a woman, facilitating rapid absorption of body liquid such as menstrual blood that will be discharged from the vaginal opening over and over again. In addition, since densities of the topsheet and the liquid absorbent layer are increased in the compressed groove, liquid applied to the absorbent region, which tends to spread in all directions through diffusion inside the topsheet and the liquid absorbent layer, may be drawn into the high-density compressed groove and then diffused along the compressed groove, effectively preventing liquid diffusion out of the absorbent region.
In the sanitary napkins disclosed in Patent Publications 1 and 2, not only the main body but also the absorbent region surrounded by the compressed groove is elongated so that the rear end of the absorbent region is located close to the rear end edge of the sanitary napkin. In the elongated sanitary napkins, since the absorbent region is thus elongated, the raised absorbent region may face the wearer's body from the anus to the cleft of the buttocks so that body liquid such as menstrual blood trying to flow down the wearer's body from the anus to the cleft of the buttocks during sleep can easily be received by the rear portion of the absorbent region.
However, if the absorbent region surrounded by the compressed groove extends close to the rear end edge of the main body, as disclosed in Patent Publications 1 and 2, body liquid such as menstrual blood having diffused rearward in the absorbent region may also come close to the rear end edge of the main body. Accordingly, when viewed from the skin-side, the sanitary napkin may look as if a large amount of menstrual blood was applied thereto, easily causing a wearer anxiety about leakage from the rear end edge of the main body.
Also in the elongated sanitary napkin, when its front portion fixed on a crotch part of an undergarment is brought into contact with the vaginal opening, this contact portion will be deformed to bulge toward the vaginal opening due to pressure from the thighs. On the other hand, the rear portion of the sanitary napkin will partially fit in the cleft of the buttocks, while the remaining large portion will be brought into contact with the convex surfaces of the buttocks. However, if the compressed groove surrounding the absorbent region extends close to the rear end edge of the main body, as disclosed in Patent Publications 1 and 2, the rear portion of the sanitary napkin may be too stiff to conform to the curved surfaces of the buttocks. As a result, a space may easily be formed between the rear portion and the wearer's buttocks, for example, such that the rear end edge on the longitudinal centerline and thereabout may easily move away from the wearer's skin.
In this regard, the distance between the rear end of the absorbent region surrounded by the compressed groove and the rear end edge of the main body may be increased to ensure a large region where menstrual blood is difficult to diffuse rearward of the absorbent region. However, if the region having no compressed groove is enlarged in the rear portion of the sanitary napkin, since the liquid absorbent layer can move relatively freely in that region, the liquid absorbent layer in the rear portion may be displaced due to body movement during sleep or the sanitary napkin may be wrinkled due to twisting of the front portion, easily causing problems of deteriorating contact between the skin-side surface and the buttocks and giving an uncomfortable feeling to the buttocks.